Octogenarian killed crossing Sydney road

A woman in her 80s has been hit and killed by a car as she tried to cross a busy road in Sydney's southwest.

The woman was attempting to cross the two-lane Narellan Road bypass just after 9am on Wednesday when she was hit by sedan, police say.

The woman died at the scene, and the driver was taken to Campbelltown Hospital to undergo mandatory drug and alcohol testing.

Narellan Road remains blocked.

Police are preparing a report for the coroner.